The goal of this study is to test the performance of a prototype noninvasive blood glucose monitor. Information from the study will be used to design a smaller and possible more accurate version of the device. patients with Type 1 diabetes will be tested in the UCSF GCRC. A glucose tolerance test will be per-formed. Blood glucose levels will be measured every 10 minutes on a Yellow Springs Instrument with blood drawn out of a double stopcock intravenous line. When the blood glucose level reaches 400 mgl, the patient will receive insulin..